Generally speaking, it is better to do hip ultrasound within 6 months after birth, because some infants may have hip dysplasia, or have hip joint effusion, etc., and timely ultrasound of the hip will help to diagnose the related diseases at this time. Congenital hip dysplasia will cause lower limb movement disorders, resulting in signs like duck walking, and timely intervention should be given to the infant, the earlier the intervention, the better the treatment effect. The earlier the intervention, the better the treatment effect. Hip ultrasound for infants, try to do within six months after birth, so as to be able to play an early diagnosis, the purpose of early intervention.